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Nanoscopic diffusion of water on a topological insulator

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  • Anton Tamtögl, Graz University of Technology, Cavendish Laboratory
  • ,
  • Marco Sacchi, University of Surrey
  • ,
  • Nadav Avidor, Cavendish Laboratory
  • ,
  • Irene Calvo-Almazán, Cavendish Laboratory, Argonne National Laboratory
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  • Peter S.M. Townsend, Cavendish Laboratory, Rutgers - The State University of New Jersey, New Brunswick
  • ,
  • Martin Bremholm
  • Philip Hofmann
  • John Ellis, Cavendish Laboratory
  • ,
  • William Allison, Cavendish Laboratory

The microscopic motion of water is a central question, but gaining experimental information about the interfacial dynamics of water in fields such as catalysis, biophysics and nanotribology is challenging due to its ultrafast motion, and the complex interplay of inter-molecular and molecule-surface interactions. Here we present an experimental and computational study of the nanoscale-nanosecond motion of water at the surface of a topological insulator (TI), Bi2Te3. Understanding the chemistry and motion of molecules on TI surfaces, while considered a key to design and manufacturing for future applications, has hitherto been hardly addressed experimentally. By combining helium spin-echo spectroscopy and density functional theory calculations, we are able to obtain a general insight into the diffusion of water on Bi2Te3. Instead of Brownian motion, we find an activated jump diffusion mechanism. Signatures of correlated motion suggest unusual repulsive interactions between the water molecules. From the lineshape broadening we determine the diffusion coefficient, the diffusion energy and the pre-exponential factor.

Original languageEnglish
Article number278
JournalNature Communications
Number of pages9
Publication statusPublished - 2020

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